<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        let i = 1;
        let j = 0;
        while (i < 101) {
            j = j + i;//j+=i
            i++;
            //j 打印写在18行 会输出所有 20行会输出一个总值和
        }
        console.log(j);
    </script>
</body>

</html>